USB: ehci_brcm_hub_control: Improve port index sanitizing

Due to (wIndex & 0xff) - 1 can get an integer greater than 15, this
can cause array index to be out of bounds since the size of array
port_status is 15. This change prevents a possible out-of-bounds
pointer computation by forcing the use of a valid port number.

Reported-by: TCS Robot <tcs_robot@tencent.com>
Signed-off-by: Haimin Zhang <tcs.kernel@gmail.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20211113165320.GA59686@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/ehci-brcm.c b/drivers/usb/host/ehci-brcm.c
index d3626bf..6a0f64c 100644 (file)
--- a/drivers/usb/host/ehci-brcm.c
+++ b/drivers/usb/host/ehci-brcm.c
@@ -62,8 +62,12 @@ static int ehci_brcm_hub_control(
        u32 __iomem     *status_reg;
        unsigned long flags;
        int retval, irq_disabled = 0;
+       u32 temp;
 
-       status_reg = &ehci->regs->port_status[(wIndex & 0xff) - 1];
+       temp = (wIndex & 0xff) - 1;
+       if (temp >= HCS_N_PORTS_MAX)    /* Avoid index-out-of-bounds warning */
+               temp = 0;
+       status_reg = &ehci->regs->port_status[temp];
 
        /*
         * RESUME is cleared when GetPortStatus() is called 20ms after start